Virologic and serologic characteristics of a natural chimpanzee lentivirus infection.

This study set out to characterize the unique features of natural lentivirus infection in chimpanzees over time. The virologic and serologic characteristics of this infection were followed longitudinally in a naturally infected chimpanzee together with a small cohort of experimentally HIV-1-infected chimpanzees. The subsequent isolates from the naturally infected chimpanzee were all non-syncytium forming (NSI) versus syncytium forming in the experimentally infected animals. In contrast to HIV-1-infected chimpanzees virus load was higher and plasma viremia occurred but in a cyclic pattern. Serologic follow-up suggested the development of neutralizing antibodies with subsequent escape of new isolates. Interestingly, the sequence of the principal neutralizing (V3 loop) domain (of HIV-1) remained constant over time. Antibodies to peptides from the V3 loop were type specific. The occurrence of persistent, fluctuating plasma viremia and NSI-type virus variants of this natural lentivirus infection are unique characteristics not previously reported in experimentally infected chimpanzees.